Probabilities of 5-year survival according to cytogenetic stratifications. (A) Probability of 5-year OS for children with advanced primary or secondary MDS according to cytogenetic stratification. Traditionally, a complex karyotype is defined by the presence of more than or equal to 3 or more than or equal to 5 aberrations. Structurally complex karyotype is defined by at least 3 chromosomal aberrations, including at least one structural aberration, excluding those with clonal evolution of monosomy 7. Karyotypes were grouped in the following hierarchical order: more than or equal to 5 aberrations, 3 or 4 aberrations, structurally complex, monosomy 7 (with or without other aberrations), normal karyotype, other karyotypes. (B) The probability of 5-year OS for children with: advanced primary or secondary MDS with structurally complex karyotype; monosomal karyotype with at least one autosomal monosomy and one or more structural aberrations that did not fulfill the criteria of a structurally complex karoytpe (“monosomal karyotype only”); monosomy 7 with or without additional aberrations, including clonal evolution of monosomy 7; normal karyotype; other karyotypes. (C) The probability of 5-year OS for patients according to cytogenetic subgroup. Patients classified as monosomal karyotype only in panel B are now included in the group of monosomy 7 (with or without additional aberrations) or other karyotypes. (D) Probability of 5-year event-free survival for patients who received allogeneic HSCT (N = 143).